#JsonCreator not deserialising #RequestParam of type enum
I am working on a Spring application where the controller is receiving list of request params that Spring is binding to a wrapper object. One of the params is of type enum where I am receiving it by some property name.
Endpoint example: http://localhost:8080/searchCustomers?lastName=Smith&country=Netherlands
#RequestMapping(value = "/search/customers", method = RequestMethod.GET)
public CustomerList searchCustomers(#Valid CustomerSearchCriteria searchCriteria)
public class CustomerSearchCriteria {
private String lastName;
private Country country;
}
public enum Country {
GB("United Kingdom"),
NL("Netherlands")
private String countryName;
Country(String countryName) {
countryName = countryName;
}
#JsonCreator
public static Country fromCountryName(String countryName) {
for(Country country : Country.values()) {
if(country.getCountryName().equalsIgnoreCase(countryName)) {
return country;
}
}
return null;
}
#JsonValue
public String toCountryName() {
return countryName;
}
}
I am expecting Spring to bind enum Country.Netherlands to CustomerSearchCriteria.country but its not doing it so. I tried similar annotations with #RequestBody and that works fine, so I am guessing he Spring binding is ignoring #JsonCreator.
Any helpful tips would be appreciated.
Here is the code that is behind #Mithat Konuk comment.
Put in your controller something like:
import java.beans.PropertyEditorSupport;
#RestController
public class CountryController {
// your controller methods
// ...
public class CountryConverter extends PropertyEditorSupport {
public void setAsText(final String text) throws IllegalArgumentException {
setValue(Country.fromCountryName(text));
}
}
#InitBinder
public void initBinder(final WebDataBinder webdataBinder) {
webdataBinder.registerCustomEditor(Country.class, new CountryConverter());
}
}
More information ca be found here: https://www.devglan.com/spring-boot/enums-as-request-parameters-in-spring-boot-rest.
Related
Spring boot 2.0.0.RELEASE
I have properties class:
#Configuration
#ConfigurationProperties(prefix="person")
public class PersonProperties {
private AddressProperties addressProperties;
public AddressProperties getAddressProperties() {
return addressProperties;
}
public void setAddressProperties(final AddressProperties addressProperties) {
this.addressProperties = addressProperties;
}
public static class AddressProperties {
private String line1;
public String getLine1() {
return line1;
}
public void setLine1(final String line1) {
this.line1 = line1;
}
}
}
And application.yml:
person:
address:
line1: line1OfAddress
It is not binding properly as my AddressProperties object is null.
When a class has the same name as yml properties AddressProperties -> Address it is working well. I tried to add Qualifier or ConfigurationProperties with a prefix address but it is not working. Unfortunately, I cannot find useful information about this case in spring docs.
How to specify a prefix for nested properties?
Property defined in yaml / property file should match with the variables defined in class.
Either change yaml file as
person:
# addressProperties will also work here
address-properties:
line1: line1OfAddress
Or define your bean as
#Configuration
#ConfigurationProperties(prefix = "person")
public class PersonProperties {
// here variable name doesn't matter, it can be addressProperties as well
// setter / getter should match with properties in yaml
// i.e. getAddress() and setAddress()
private AddressProperties address;
public AddressProperties getAddress() {
return address;
}
public void setAddress(AddressProperties address) {
this.address = address;
}
}
If you want to get all properties under address without defining them in separate bean you can define your PersonProperties class as
#Configuration
#ConfigurationProperties(prefix = "person")
public class PersonProperties {
private Map<String, Object> address;
public Map<String, Object> getAddress() {
return address;
}
public void setAddress(Map<String, Object> address) {
this.address = address;
}
}
Here PersonProperties#address will contain {line1=line1OfAddress}
Now All properties under address will be in the Map.
You could simply un-nest the two classes, allowing each to have it's own prefix.
First class:
#Configuration
#ConfigurationProperties(prefix="person")
public class PersonProperties {
private AddressProperties addressProperties;
public AddressProperties getAddressProperties() {
return addressProperties;
}
public void setAddressProperties(final AddressProperties addressProperties) {
this.addressProperties = addressProperties;
}
}
Second class:
#Configuration
#ConfigurationProperties(prefix="person.address")
public class PersonAddressProperties {
private String line1;
public String getLine1() {
return line1;
}
public void setLine1(final String line1) {
this.line1 = line1;
}
}
Edit: As was pointed out in the comments, you'd have to inject both of these classes if one block of code needed to refer to both sets of properties.
During the last hours I read many StackOverflow questions and articles, but none of the advices helped. What I tried:
Add #JsonCreator and #JsonProperty to both Person and Employee classes (link)
Add #JsonDeserialize(using = EmployeeDeserialize.class) to Employee class (link)
Add Lombok as dependency, set lombok.anyConstructor.addConstructorProperties=true and add #Data / #Value annotation to both Person and Employee classes (link)
Finally, I did the deserialization manually:
String json = "{\"name\": \"Unknown\",\"email\": \"please#work.now\",\"salary\":1}";
ObjectMapper objectMapper = new ObjectMapper();
Employee employee = objectMapper.readValue(json, Employee.class);
In this way I could deserialize the JSON, but as soon as I started my spring-boot-starter-web project and called
http://localhost:8080/print?name=unknown&email=please#work.now&salary=1
I got the good old BeanInstantiationException
Failed to instantiate [Employee]: No default constructor found
I run out of ideas. Does anybod know why this worked when I did the deserialization manually? And why it throws exception when I call the REST endpoint?
#SpringBootApplication
public class Application {
public static void main(String[] args) {
SpringApplication.run(Application.class, args);
}
}
#RestController
public class EmployeeController {
#GetMapping("print")
public void print(Employee employee) {
System.out.println(employee);
}
}
public class Person {
private final String name;
#JsonCreator
public Person(#JsonProperty("name") String name) {
this.name = name;
}
public String getName() {
return name;
}
}
public class Employee extends Person {
private final String email;
private final int salary;
#JsonCreator
public Employee(
#JsonProperty("name") String name,
#JsonProperty("email") String email,
#JsonProperty("salary") int salary) {
super(name);
this.email = email;
this.salary = salary;
}
public String getEmail() {
return email;
}
public int getSalary() {
return salary;
}
}
You’re implementing JSON deserialisation, yet you’re not using any JSON.
Change to use #PostMapping on your controller method and use something like Postman or cURL to send the JSON to your /print endpoint.
For some reason I am not able to hide protected fields (without setter), via ObjectMapper configuration, from being serialized to a JSON string.
My POJO:
public class Item {
protected String sn;
private String name;
public Item(){
sn = "43254667";
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public String getSn() {
return sn;
}
}
My mapper:
mapper.setVisibility(PropertyAccessor.SETTER, Visibility.PUBLIC_ONLY);
mapper.setVisibility(PropertyAccessor.GETTER, Visibility.PUBLIC_ONLY);
mapper.setVisibility(PropertyAccessor.FIELD, Visibility.NONE);
The output is:
{
"sn" : "43254667",
"name" : "abc"
}
UPDATE: I cannot modify the Item class, hence I cannot use annotations.
Use #JsonIgnore
You could annotate the field or method with #JsonIgnore.
It's a marker annotation that indicates that the annotated method or field is to be ignored by introspection-based serialization and deserialization functionality.
Use as following:
public class Item {
#JsonIgnore
protected String sn;
...
}
Or as following:
public class Item {
...
#JsonIgnore
public String getSn() {
return sn;
}
}
Use #JsonIgnore with mix-ins
Based on your comment, you could use mix-in annotations when modifying the classes is not an option, as described in this answer.
You can think of it as kind of aspect-oriented way of adding more annotations during runtime, to augment statically defined ones.
First, define a mix-in annotation interface (class would do as well):
public interface ItemMixIn {
#JsonIgnore
String getSn();
}
Then configure your ObjectMapper to use the defined interface as a mix-in for your POJO:
ObjectMapper mapper = new ObjectMapper();
mapper.addMixIn(Item.class, ItemMixIn.class);
For extra details, check the documentation.
Use a BeanSerializerModifier
Based on your comment, you may consider a BeanSerializerModifier, as following:
public class CustomSerializerModifier extends BeanSerializerModifier {
#Override
public List<BeanPropertyWriter> changeProperties(SerializationConfig config,
BeanDescription beanDesc, List<BeanPropertyWriter> beanProperties) {
// In this method you can add, remove or replace any of passed properties
return beanProperties;
}
}
Then register the custom serializer as a module in your ObjectMapper.
ObjectMapper mapper = new ObjectMapper();
mapper.registerModule(new SimpleModule() {
#Override
public void setupModule(SetupContext context) {
super.setupModule(context);
context.addBeanSerializerModifier(new CustomSerializerModifier());
}
});
You've instructed your mapper to serialize public getters:
mapper.setVisibility(PropertyAccessor.GETTER, Visibility.PUBLIC_ONLY);
That's why Jackson will serialize the sn field (You have a public getter here in the end).
To get rid of the serialized sn field, simply annotate your getter with #JsonIgnore:
public class Item{
protected String sn;
private String name;
public Item(){
sn = "43254667";
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
#JsonIgnore
public String getSn() {
return sn;
}
}
If you cannot annotate your class, you can always write a custom serializer for your POJO or use Mixins
I have a simple project, based on this guide. I created a simple REST interface and I want it to use my database. I added Hibernate to the dependencies and created the DAO class. I'm using Spring Tool-Suite for IDE. As far as I understand I should add some beans to tell the classes what to use but I don't understand how. Here are my classes.
Application.java
package com.learnspring.projectfirst;
#SpringBootApplication
public class Application {
public static void main(String[] args) {
SpringApplication.run(Application.class, args);
}
}
Marker.java
package com.learnspring.projectfirst;
#Entity
public class Marker {
#Id
#Column
#GeneratedValue(strategy=GenerationType.AUTO)
private long id;
#Column
private double longitude;
#Column
private double latitude;
#Column
private String address;
public Marker() {
// Empty constructor
}
public Marker(long id, double longitude, double latitude, String address) {
this.id = id;
this.longitude = longitude;
this.latitude = latitude;
this.address = address;
}
//Getters and Setters
}
MarkerController.java
package com.learnspring.projectfirst.controller;
#Controller
public class MarkerController {
private Logger logger = Logger.getLogger(MarkerController.class.getName());
#Autowired
private MarkerServiceImplementation markerService;
#RequestMapping(value="/markers", method=RequestMethod.GET)
public #ResponseBody List<Marker> getMarkers(#RequestParam(value="city", defaultValue="") String city) {
return this.markerService.getAllMarkers();
}
#RequestMapping(value="/markers/new", method=RequestMethod.POST)
public #ResponseBody Marker addMarker(#RequestBody Marker marker) {
this.markerService.addMarker(marker);
return marker;
}
}
MarkerDaoImplementation.java
package com.learnspring.projectfirst.dao;
#Repository
public class MarkerDaoImplementation implements MarkerDaoInterface {
#Autowired
private SessionFactory sessionFactory;
#Override
public void addMarker(Marker marker) {
this.sessionFactory.getCurrentSession().save(marker);
}
#Override
public void deleteMarker(int markerId) {
this.sessionFactory.getCurrentSession().delete(this.getMarker(markerId));
}
#Override
public Marker getMarker(int markerId) {
return (Marker) this.sessionFactory.getCurrentSession().get(Marker.class, markerId);
}
#Override
public List<Marker> getAllMarkers() {
return this.sessionFactory.getCurrentSession().createQuery("from Marker").list();
}
}
MarkerServiceImplementation.java
package com.learnspring.projectfirst.service;
#Service
public class MarkerServiceImplementation implements MarkerServiceInterface {
#Autowired
private MarkerDaoImplementation markerDao;
#Transactional
public void addMarker(Marker marker) {
this.markerDao.addMarker(marker);
}
#Transactional
public void deleteMarker(int markerId) {
this.markerDao.deleteMarker(markerId);
}
#Transactional
public Marker getMarker(int markerId) {
return this.markerDao.getMarker(markerId);
}
#Transactional
public List<Marker> getAllMarkers() {
return this.markerDao.getAllMarkers();
}
}
And here is the file structure:
I understand that I should tell my program the database name and the columns using beans but I don't understand how. How can I link the java code to the beans? Sorry I pasted so much code, I just wanted to make sure you have everything needed. Thank you in advance!
This is the one you need: Spring Boot with MySQL
Refer this example : Spring MVC with JdbcTemplate Example
The annotations in your "Marker" class determine the MySQL table and column names (based on the class and class variable names). The tablename will be "marker", with the columns "id", "longitude", "latitude", "address".
You forgot the most important part in your code: your spring configuration. it determines how the SessionFactory instance will be initialized before being injected into your DAO class. Here you have to set an appropriate connection to the MySQL Server (e.g. via an JNDI Resource)
I have implemented my validation for list of custom class as mention in this post. For reference here my code looks like
class TopDtoForm {
#NotEmpty
private String topVar;
private List<DownDto> downVarList;
//getter and setter
}
class DownDto {
private Long id;
private String name;
//getter and setter
}
#Component
public class TopDtoFormValidator implements Validator {
#Override
public boolean supports(Class<?> clazz) {
return TopDtoForm.class.equals(clazz);
}
#Override
public void validate(Object target, Errors errors) {
TopDtoForm topDtoForm = (TopDtoForm) target;
for(int index=0; index<topDtoForm.getDownVarList().size(); index++) {
DownDto downDto = topDtoForm.getDownVarList().get(index);
if(downDto.getName().isEmpty()) {
errors.rejectValue("downVarList[" + index + "].name", "name.empty");
}
}
}
}
So even I send empty name binding result has 0 error. I tested with topVar and it is working fine. My question is do I have to do any other configuration to say use this validator?
Thanks
In Spring MVC just annotate in TopDtoForm your list with #Valid and add #NotEmpty to DownDto. Spring will validate it just fine:
class TopDtoForm {
#NotEmpty
private String topVar;
#Valid
private List<DownDto> downVarList;
//getter and setter
}
class DownDto {
private Long id;
#NotEmpty
private String name;
//getter and setter
}
Then in RequestMapping just:
#RequestMapping(value = "/submitForm.htm", method = RequestMethod.POST) public #ResponseBody String saveForm(#Valid #ModelAttribute("topDtoForm") TopDtoForm topDtoForm, BindingResult result) {}
Also consider switching from #NotEmpty to #NotBlank as is also checks for white characters (space, tabs etc.)